Many types of high-pressure piston pumps of the radial type include at least one spring-loaded piston which terminates at its rear end in a coaxial spherical section, such section being operably receivable within a socket bore sleeve which is adapted for sliding movement within a chamber. Such sleeve member, which may have a rear surface associated with an eccentric shaft in a known manner, is generally given a limited capability for oscillation with respect to the mating spherical section of the piston. Conventional designs of this type are described, e.g., in German published applications Nos. 1,528,501, 1,403,748, and 2,030,358, and in Czechoslovakian Pat. No. 442,021.
In all known arrangements of this type, the sub-assembly of the piston and the sleeve is generally complex and expensive, and such known constructions are not adaptable to facilitate easy disconnection of the two halves of the sub-assembly for pump maintenance and other purposes. In addition, the known couplings of the spherical section of the piston to the mating spherical recess in the socket member afford little or no play in a movement of the sleeve, so that it is difficult to adjust the sleeve to correct for errors in the movement of the piston.